Thermoplastic compounds, unlike wood, metal, or glass, do not rot, rust, or shatter. For that reason, the world in the past seventy years has seen a revolution in material science arising from the combination of a thermoplastic resin and one or more functional additives to provide specific properties to the resin.
Unlike wood but like metal and glass, at a given temperature, a thermoplastic resin can melt. Its processing versatility benefits from its capacity to mix with the functional additives while in a molten state.
But in use, the exposure of a fully formed thermoplastic article to excessive heat or flame can be quite detrimental to property and person.
Flame retardants, drip suppressants, mineral fillers, and char formers are functional additives which can be used to help the thermoplastic compound to retard the effects of heat or flame from melting or even burning. Flame retardant thermoplastic compounds are particular needed when the plastic article is used in any confined space where persons might be present during any condition, planned or emergency, which might expose the plastic article to such excessive heat or flame.
Non-halogenated flame retardants have recently become popular because they minimize the release of halogenated chemicals if the plastic article would begin to degrade, melt, or burn.
To reduce the possibility of the plastic article dripping as it melts, polytetrafluoroethylene (PTFE) is often used as a drip suppressant. But PTFE, even in very small amounts, is a halogenated material, albeit fluorinated rather than chlorinated.